配置SSH无秘钥登录

[hadoop@hadoop01 ~]$ cd .ssh
[hadoop@hadoop01 .ssh]$ ll -d ./　　#查看.ssh文件夹的权限
drwx------. 2 hadoop hadoop 4096 Jun 19 23:44 ./　　#.ssh文件夹的权限为700，如果不是，必须执行chmod 700 ./进行修改，否则，即使配置了无密钥登录后面仍然需要密码
[hadoop@hadoop01 .ssh]$ ls
authorized_keys  id_rsa  id_rsa.pub  known_hosts
[hadoop@hadoop01 .ssh]$ rm -rf ./*　　#清空文件夹
[hadoop@hadoop01 .ssh]$ ssh-keygen -t rsa　　#生成公钥和秘钥
Generating public/private rsa key pair.
Enter file in which to save the key (/home/hadoop/.ssh/id_rsa):
Enter passphrase (empty for no passphrase):
Enter same passphrase again:
Your identification has been saved in /home/hadoop/.ssh/id_rsa.
Your public key has been saved in /home/hadoop/.ssh/id_rsa.pub.
The key fingerprint is:
a2:78:65:72:49:9a:71:91:aa:8f:3b:3e:a8:b3:74:87 hadoop@hadoop01.zjl.com
The key's randomart image is:
+--[ RSA 2048]----+
|      ..         |
|      ..         |
|    ..o          |
|    .* .         |
|   .+ * S        |
|  ...* .         |
| o.Eo.           |
|+ =.o            |
|++o+             |
+-----------------+
[hadoop@hadoop01 .ssh]$ ll
total 8
-rw-------. 1 hadoop hadoop 1675 Jun 19 23:41 id_rsa　　#秘钥
-rw-r--r--. 1 hadoop hadoop  405 Jun 19 23:41 id_rsa.pub　　#公钥

[hadoop@hadoop01 .ssh]$ ssh-copy-id hadoop02.zjl.com　　#将公钥发送给远程主机
The authenticity of host 'hadoop01.zjl.com (192.168.0.131)' can't be established.
RSA key fingerprint is 60:10:35:2f:64:08:bf:82:e5:bc:56:8c:3d:60:18:13.
Are you sure you want to continue connecting (yes/no)? yes
Warning: Permanently added 'hadoop01.zjl.com,192.168.0.131' (RSA) to the list of known hosts.
hadoop@hadoop01.zjl.com's password:
Now try logging into the machine, with "ssh 'hadoop01.zjl.com'", and check in:

  .ssh/authorized_keys

to make sure we haven't added extra keys that you weren't expecting.

[hadoop@hadoop01 .ssh]$ ssh hadoop01.zjl.com　　#无密码登录

 Last login: Mon Jun 19 23:30:46 2017 from 192.168.0.1
[hadoop@hadoop02 ~]$　　#无密码登录成功

　　所谓公钥登录，就是用户将自己的公钥储存在远程主机上。登录的时候远程主机回向用户发送一段随机字符串，用户用自己的秘钥加密后再发送给远程主机。远程主机用事先储存的公钥进行解密，如果成功，就证明用户是可信的，直接允许登录shell，不再要求密码。